The invention relates to a battery management system comprising input means for receiving input signals representative of a physical quantity of a battery and processing means for calculating at least one physical quantity of the battery at least partially based on the input signals and a battery temperature; and for generating an output signal derived from the calculated physical quantity. The invention also relates to a smart battery comprising a battery management system. The invention further relates to a battery charger/discharger comprising a battery management system.
The invention also relates to a battery simulator comprising: input means for receiving an input value of at least one parameter representative of a physical quantity of a battery; and processing means for calculating at least one characteristic of a physical quantity of the battery at least partially based on the input value and a battery temperature; and for generating an output characteristic derived from the calculated characteristic of the physical quantity. The invention further relates to a method for simulating a behaviour of a battery; the method comprising receiving an input value of at least one parameter representative of a physical quantity of the battery; calculating at least one characteristic of a physical quantity of the battery at least partially based on the input value and a battery temperature; and generating an output characteristic derived from the calculated characteristic of the physical quantity.
The invention further relates to a method for producing a battery, comprising simulating a characteristic of the battery, and producing the battery according to the generated output characteristics.
The application of rechargeable batteries and, particularly, of sealed rechargeable batteries in portable electronic products is rapidly growing. Important application areas are portable computers (notebooks, PDAs, game computers, etc.), mobile phones, portable audio equipment, camcorders and various other cordless products, such as shavers, vacuum cleaners, or screw-drivers. From a consumer's point of view a longer playing time and a longer life-time of battery driven products are key factors in determining their attractive power. For many products it is important that the consumer is informed of the actual State of Charge (SoC) of the battery. This is particularly the case for devices, such as mobile phones or camcorders, which may be used outside the reach of power supplies, allowing the user to determine whether the battery needs to be recharged while the user still has access to a power supply. Increasingly Battery Management Systems (BMSs) are used for, depending on the application, realising fast and efficient battery charging, allowing exploitation of a substantial part of the available battery capacity, or providing information, such as the state of charge, to the user. The battery management system may be integrated with the battery (forming a so-called smart-battery), added to a battery in a fixed smart battery pack, used in a quick-charger, or implemented in a consumer product. It will be understood that the term battery relates not only to a single battery cell but also to a group of batteries used in series or parallel, or a combination of both.
The patent application NL 9001578 describes a battery management system wherein an input signal, which represents a physical quantity of the battery, such as battery voltage, charge or discharge current and battery temperature, is sampled regularly, for instance every second. The battery management system uses a model, describing the physical behaviour of the battery, to generate as the output signal an indication of the State of Charge based on the present and historic measurements. After each new measurement the previous State of Charge value is updated by subtracting the discharge current (I.sub.d) for the sampling period and adding the charge current (I.sub.c) for the sampling period multiplied by a charge efficiency parameter ETA (SoC.sub.n =SoC.sub.n-1 -I.sub.d /3600+ETA*I.sub.c /3600, where the SoC is given in Ah). Also an accumulated charge and discharge current are calculated. Whenever a predetermined "full" or "empty" charge state is reached, the accumulated measurements are used to readjust the charge efficiency parameter. The model is programmed in software and executed by a processor. The known system is limited to indicating the State of Charge. The system uses a physical model, which uses the charge and discharge current as input. No use of other inputs for determining the State of Charge is described. The accuracy of the system is limited, particularly when the predetermined "full" or "empty" charge states are not frequently reached.